Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 280805 CCA
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
400 AM EDT FRI AUG 28 2015

.SYNOPSIS...A FRONTAL ZONE WILL HOLD JUST OFF THE NORTH CAROLINA
COAST THROUGH THE WEEKEND... WHILE HIGH PRESSURE BUILDS INTO THE
REGION FROM THE NORTH.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 300 AM FRIDAY...

HIGH PROBABILITY OF A DRY DAY WITH GENERALLY MOSTLY SUNNY SKIES FOR
CENTRAL NC. THE LATEST SURFACE ANALYSIS SHOWS THE FRONTAL ZONE WELL
TO OUR SOUTH AND SE... AND THE SURFACE HIGH CENTERED OVER WRN NY/PA
NOSING SOUTHWARD INTO CENTRAL NC. THIS CONFIGURATION WILL PERSIST
TODAY WITH DEEPLY DRY AIR FILTERING IN... INCLUDING FALLING SURFACE
DEWPOINTS DOWN THROUGH THE 50S... AND MUCH BELOW NORMAL PW VALUES.
WITH MID LEVEL RIDGING NOSING IN FROM THE SE AND THE LACK OF BOTH
FORECAST CAPE AND DEEP LAYER SHEAR... WILL KEEP A DRY FORECAST. HIGH
THIN CLOUDS WILL CONTINUE TO STREAM IN ON THE EAST SIDE OF THE WEAK
SHEAR AXIS TO OUR WEST... PARTICULARLY EAST OF HIGHWAY 1... BUT MOST
AREAS ESPECIALLY WEST SHOULD SEE CONSIDERABLE SUNSHINE TODAY.
THICKNESSES AND STATISTICAL GUIDANCE SUPPORT HIGHS IN THE MID-UPPER
80S... VERY CLOSE TO SEASONAL NORMALS. EXPECT FAIR SKIES TONIGHT
WITH BELOW-NORMAL LOWS AROUND 60-65. -GIH

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
AS OF 305 AM FRIDAY...

DRY WEATHER LOOKS LIKELY TO CONTINUE... ALTHOUGH WE SHOULD SEE
THICKENING CLOUD COVER ESPECIALLY SAT NIGHT WITH A SLIGHT RECOVERY
IN HUMIDITY. THE SURFACE HIGH TO OUR NORTH WILL SLIP EASTWARD OFF
THE MIDATLANTIC COAST AND WEAKEN... ALTHOUGH A WEAK MODIFIED
SOUTHERN PORTION OF THIS RIDGE WILL BREAK OFF AND SETTLE OVER THE
SRN APPALACHIANS AND ADJACENT PIEDMONT THROUGH SAT NIGHT... KEEPING
THE LOW LEVELS FAIRLY DRY. PW VALUES ARE PROJECTED TO STAY AOB 1
INCH INTO SAT EVENING... ALTHOUGH SW SECTIONS OF THE CWA WILL SEE PW
HEAD BACK UP TOWARD 1.25-1.5 INCHES AS MOISTURE SURGES BACK INLAND
ACROSS GA AND SC INTO AL AND SW NC. THIS WILL OCCUR AHEAD OF A WEAK
MID LEVEL LOW THAT WILL LIFT NORTHWARD FROM THE NORTH CENTRAL GULF
THROUGH MS/AL... DRAWING INCREASED DPVA ACROSS GA INTO THE
WRN/CENTRAL CAROLINAS. BUT MUCH OF CENTRAL NC WILL HOLD WITHIN A
FAIRLY DRY AIR MASS WITH NO TRIGGER TO FORCE ASCENT... AND DESPITE
THE GRADUAL INCREASE IN CLOUDS ESPECIALLY OVER THE SOUTH AND WEST
LATE SAT INTO SAT NIGHT... WILL KEEP PRECIP CHANCES OUT OF THE
FORECAST. HIGHS ONCE AGAIN SHOULD BE IN THE MID 80S TO NEAR 90...
PERHAPS A COUPLE OF DEGREES ABOVE TODAY`S HIGHS AS THICKNESSES RISE
WHILE STAYING JUST SLIGHTLY BELOW NORMAL. LOWS 63-68 SAT NIGHT WITH
A TREND TO PARTLY TO MOSTLY CLOUDY SKIES. -GIH

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 355 AM FRIDAY...

THE MODELS INDICATE THAT A CLOSED LOW CENTERED NEAR THE CENTRAL GULF
COAST THIS MORNING WILL EJECT NORTHEASTWARD AS A SHORTWAVE TROUGH
THROUGH THE SOUTHERN AND CENTRAL APPALACHIANS SUN-SUN NIGHT...WITH
THE PAST COUPLE OF RUNS OF THE ECMWF OUT-PACING THE PREFERRED
AMERICAN MODELS BY 6-12 HOURS WITH THE TIMING OF THIS FEATURE.

THE ASSOCIATED FORCING FOR ASCENT WILL OVERSPREAD THE WESTERN
CAROLINAS DURING PEAK HEATING...OR SHORTLY THEREAFTER WITH
NORTHEASTERN EXTENT INTO THE NC SOUTHERN AND WESTERN NC
PIEDMONT...WHICH IN CONJUNCTION WITH BOTH GRADUALLY INCREASING DEEP
MOISTURE IN SW FLOW AND A WEAKENING CAP ALOFT...SHOULD PROVE
SUPPORTIVE OF SCATTERED SHOWERS AND STORMS INVOF THE YADKIN RIVER
AND ESPECIALLY WEST/IN THE MOUNTAINS...WHERE LOWER LEVEL
FORCING/DIFFERENTIAL HEATING WILL BE MORE LIKELY TO COMPENSATE FOR A
STILL RELATIVELY DRY BOUNDARY LAYER CHARACTERIZED BY SFC DEWPOINTS
IN THE LOW-MID 60S. SOME OF THIS ACTIVITY COULD LINGER OVERNIGHT
OVER THE PIEDMONT...AS THE S/W TROUGH TRACKS INTO WESTERN NC. NEAR
CLIMO TEMPERATURES IN THE MID-UPPER 80S AND MID-UPPER 60S.

THE MODELS CONTINUE TO SUGGEST ADDITIONAL SHORTWAVE ENERGY WILL
AMPLIFY INTO THE SOUTHERN PLAINS TO LOWER-MID MS VALLEY AND
EFFECTIVELY CAUSE THE PATTERN ALOFT TO RETROGRADE
(DISCONTINUOUSLY)...AND CONSEQUENTLY ALLOW THE SUB-TROPICAL RIDGE
BULGE WESTWARD ALONG THE SOUTHEAST US COAST. AT THE SAME TIME...A
SEPARATE RIDGE ALOFT IS FORECAST TO BUILD ACROSS THE OH VALLEY AND
GREAT LAKES...AND THE RESULT IN RECENT MODEL RUNS IS A SLOWER AND
MORE WEST AND SOUTHWARD SUPPRESSED TRACK OF ERIKA.

ANY ASSOCIATED TROPICAL MOISTURE OR AFFECTS ON CENTRAL NC WOULD
LIKELY NOT OCCUR UNTIL MID-WEEK...AND EVEN THAT WILL BE CONDITIONAL
ON 1) ERIKA NOT DISSIPATING ENTIRELY AS IT TRACKS WEST OR NORTHWEST
THROUGH A HOSTILE ENVIRONMENT DURING THE NEXT DAY OR TWO...AND 2)
THE AFOREMENTIONED BUILDING RIDGE NOT COMPLETELY SUPPRESSING THE
SYSTEM --OR WHAT IS LEFT OF IT-- SOUTH AND WEST OF OUR REGION
THROUGHOUT THE FORECAST PERIOD.

GIVEN THE UNCERTAINTY AND POSSIBLE MINIMAL AFFECT FROM ERIKA...HAVE
TRENDED THE FORECAST TOWARD CLIMO FOR THE UPCOMING WEEK...WITH
SLIGHT-CHANCE DIURNAL POP AND TEMPERATURES NEAR TO SLIGHTLY ABOVE
AVG.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 145 AM FRIDAY...

HIGH CONFIDENCE IN VFR CONDITIONS FOR THE NEXT 24 HOURS AT ALL
CENTRAL NC TERMINALS. THE FRONTAL ZONE HAS PUSHED ESE OF THE AREA AS
HIGH PRESSURE CENTERED OVER PA/NY BUILDS SOUTHWARD... NOSING INTO
CENTRAL NC AND BRINGING LOW LEVEL DRY AIR THAT WILL INHIBIT
FORMATION OF ANY FOG/STRATUS THIS MORNING. THE MID LEVEL TROUGH AXIS
JUST TO OUR WEST AND THE RESULTING FLOW ALOFT FROM THE S AND SW WILL
ALLOW CONSIDERABLE HIGH THIN CLOUDINESS TODAY/TONIGHT... WITH VFR
CIGS AOA 20 KFT... ALTHOUGH CIGS WILL START TO LOWER TO AROUND 12-15
KFT TOWARD THE END OF THE TAF VALID PERIOD TONIGHT... AS A WEAK LOW
OVER THE NORTH CENTRAL GULF OF MEXICO LIFTS NORTHWARD THROUGH MS/AL
INTO TN... BRINGING WEAK DISTURBANCES NORTHWARD INTO NC.

LOOKING BEYOND 06Z EARLY SAT MORNING: HIGH CONFIDENCE THAT CIGS WILL
LOWER BELOW 10 KFT BUT REMAIN VFR THROUGH AT LEAST SUNDAY. AS THE
SURFACE HIGH MOVES OFFSHORE... INCREASING MOISTURE MAY BRING A
RETURN TO SCATTERED AFTERNOON SHOWERS OR STORMS TUE... BUT OVERALL
EXPECT VFR CONDITIONS TO PERSIST INTO MIDWEEK. -GIH

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...26
AVIATION...HARTFIELD


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